Lubricating oil



Patented Feb. 6, 1934 Continental-Oil Gompa'ny, Ponca City, Okla acorporation of Delaware No Drawing. Application v Serial N0. 600,368 t1: Claim. (01. ti-=9)" My invention relates to improvements in lubric.acids in lubricants are given to clarify their accating oils, and to amethod for increasing their lubricity.

For a number of years it has been-generally known that the final qualityof a lubricating oil depended on something other than the viscosity ofthe hydrocarbon oil. This has been found to be particularly true whenthe lubricant is used under conditions of thin film or boundary lubrb location in which the layer: of lubricating oil between the rubbingsurfaces is very thin. It has been found that some oils act as betterlubrilubrication even though their viscosities at the temperature, ofuse are substantially the same.

The property of one oil which makes it a better lubricant than anotherunder these conditions has been designated as unctuosity (pr-oiliness Itis known that hydrocarbon lubricants care- 80 fully prepared from thevery best lubricating oil stocks are, as a rule, deficient inoilinesscharacteristics even though they are otherwise of the highestquality. This fact has worked a considerable hardship on the lubricatingoil manufacturer and'the mechanical engineer. Practically all mechanicaldevices must operate partly in the field of boundary lubrication underwhich condition the coeflicient of friction, and therefore themechanical wear, is excessive withlubri- 80 cents of low oiliness value.I I

Under these conditions the excessive mechanical wear is not the onlyobjectional result of the increased'coefflcient of friction. It has alsobeen found that excessive temperatures at the point of friction consumelarge quantities of the lubricant and that more'fuel is required toovercome the friction. r 1

I have found that, the addition of small quantities of hydroxy fattyacids and the like to 40 hydrocarbon lubricants increases the unctuosityor oilinessiof the hydrocarbon lubricant. With the increase in oilinessthe coeflicient'of friction of the hydroxy acidhydrocarbon lubricant isless than that of the original hydrocarbon lubricant when tested by theHerschel oiliness testing machine.

Hydrocarbon lubricants containing small amounts of hydroxy acid make anideal lubricant for operation in the field of boundary lubrication andin the field of fluid or viscous lubrication.

There is some indication of lower engine temperatures, less fuelconsumption, higher critical temperatures for the lubricant, and lesschange in lubricating value due to unburned fuel dilution as well aslowering the coefllcient of friction.

-, and very *dimcult to remove. pletely removed with ordinaryhydrocarbonand cants than othersunder conditions of boundary film. may result-fromthe chemical action of the The following theories of the action ofhydroxy tion, but should not be consideredas a limitation to thisdisclosure which is independent of any or all theories projected.

There is. considerable evidence that the hyidroxy fatty acid inthe-hydrocarbon oil acts as an acidand forms a soap with the metallicsurfaces with; which itcomes in contact. The oiliness film formed by thefatty acid is very stable as It cannot be comhydroxy acid solvents;therefore, the oiliness hydroxyfatty acid and the metal surfaces.

Long carbon chain hydroxy fatty acid mole cules are polar bodies andtheir afllnity for metal and general action acteristic; I I

maybe a result of this char- Thechief theoryon which my invention isbased is found in thereahn of colloid chemistry.

-Heavy lubricating oils may exist in the category of viso-colloids, i.e. poly-phase systems in which the disperse component is of the samechemical nature as the dispersion medium, so in heavy lubricating oilsthe disperse phase is a molecular aggregate suspended in a dispersionmedium of simpler and similar structure. This conception explains thehigh viscosity, the large temperature coeflicient of viscosity and thehysteresiseflects which have been observed with heavy lubricating oils.Thenaccording'to this theory the reduction in coemcient of friction bythe addition .of hydroxy fatty acids may be due to two causes (1) theincreased dispersity of the disperse-phase and (2) the lowering ofinterfacial tension. The hyperdefiocculation of the disperse phaseenables the metal of the bearing to adsorb the oil. The evidencesupports this theory. A bearing lubricated with the oil ofmyinvention'ha's been polished and. by means of microphotographs, it hasbeen determined that'the oil has'beenadsorbed by the pores of the metal.It will be understood that the=-pores are of a;:microsc0pic size, sothat only a hyperdispersed phase will be adsorbed thereby. After the oilof my invention had been used to lubricate an automobile engine, the oilhas been drained out, and the automobile has been driven without oil forover thirty miles without injurious effects, it having been lubricatedby the adsorbed oil. A given quantity of the oil of my invention may beplaced in a sealed metal container for a length of time. It will befound that there is an apparent loss in the quantity of oil. If the samecontainer be used again, the no for the heavier, higher viscosityhydrocarbon lu bricants. Mono, di and trihydroxyacids are contemplatedwithin the scope of this invention The commercial application of thisinvention is limited to those hydroxy fatty acids found be economicallyproduced from raw materials on the market in sufliciently large 1quantities. Therefore the hydroxy acids mentioned are of commercialvalue but do not 'acttas a limitation to the invention because'a sourceof supply of other hydroxy acids may be found whichJnay justify use.

Hydroxy stearic acids'are valuable assepa rate individual compounds or.as blends of the 1 various hydroxy stearic compounds The productpreparedfrom oleic acid by oxidation with an alkaline solution of potassiumpermanganate is suitable. The crude product contains .dihydroxy stearicacid and possiblydibasic acids due to the continued oxidation of thehydroxyl group. The hydroxyl group is substituted at the unsaturatedhydrocarbon; therefore, the hydroxyl groups may be on the8-9 or 9-10carbon atoms, depending upon the point of .unsaturation of the originaloleic acid. s

Treating oleic acid in a petroleum ether solution with concentratedsulfuric acid yields a hydroxystearic aciddifferent fromthe above, whichmay beused in this invention. A greater concentration' of the hydroxyacid is obtained by removing the unchanged oleic acid fromthe-solutionand treating it again in-the same manner. The crude product issatisfactory for this invention.

Ricinoleic acid as recovered from the -saponiflcationof castor oil issatisfactory for-use in'this invention. The crude product is not .purericin- 'oleicacid, but the impurities present do not have anobjectionable influence on the-invention;

fled; Mild oxidation of ricinoleic acid with alkaline potassiumpermanganate in the cold gives a trihydroxyacid which may be utilized.

vRicinelaidic acidand elaidic acid may be used in this invention. Theseproductsare prepared from ricinoleic and oleic acid respectively, andare stereometrical isomerides of the original acid. Nitrous acid fumesacting on the original acid in the cold yield the isomeride,-which maybe used in the crude state after removing any excess nitrous oxidefumes. Oxidation of elaidic acid with potassium permanganate yields adihy- F constituents.

with the hydro'carbon oil.

and the like. Y

- It willbe understood that certain features, subdroxystearic aciddiffering in some respects from the dihydroxystearic acid obtained bythe oxidation of oleic acid. Further oxidation of ricinelaidio acidyields a trihydroxylated acid mixture, which may be employed in thecrudestate.

' It is advisable to make blends of some of the hydroxy acids with eachother and with other fatty acids. These blends are advantageous incontrolling the solubility of the various hydroxy acids in the varioushydrocarbon lubricants. Knowing the character of the hydroxy acid oracid mixture and the character of the hydrocarhon oil, the blend of onewith another depends uponthe percentage of total acid required in the pv finished lubricant and their degree of solubility large quantities orthose fatty acids which canx atthe temperature of use.

The fatty acids and the hydroxy fatty acids form constant boilingeutectics with each other, which have properties not, similar to any ofthe This characteristic is used in blending hydroxy acids in petroleumhydrocarbons, the constant boiling fraction of the various blends of thehydroxyacids with each other and with other fatty acidsv being blendedwith the petroleum hydrocarbon'instead of the original hydroxyacid. U"In practicing my invention the .hydroxyacid,

"mixture'or eutectic is added to and well'blended' The percentage of thehydroxyacid mixture or eutectic added is rather small and depends uponthe conditions of use of thelubricant and the character-of thepetroleumhydrocarbon oil. The

quantity is less than 100 grams per gallon of lubricant and usuallyamounts to about 35 to grams per gallon for the various types ofhydroxyacids combinations and operations are of utility and maybeemployed without reference to'other fea "tures and sub-combinations;This is contemplated by and is within the scope of my claim. It isfurther obvious that various changes may be made in details, within thescope of my claim, without departing from the spirit of my invention, Itis-therefore to be understood that my invention is not 'to' be limited:to the specific details de'scribed.

Having thus described my invention, what I claim is: therefore theexpense of purification is not justi- 'A lubricant comprising incombination a hydrocarbon oil existing as an isocolloidal system havingan external and an internal phase, and from 35 to 100 grams per gallonof said oil of adeflocculating agent adapted to increase the dispersionofthe internal phase, said deflocculating agent consisting of anoxidation product obtained by oxidi'zin'ga sterecmetrical isomeride ofoleic acid with potassium permanganate, said stereometri'cal isomeridebeing obtained by reacting oleic acid with nitrous acid;

BERT H. LINCOLN.

